title: Study of force induced melting of dsDNA as a function of length and conformation.
abstract: We measure the constant force required to melt double-stranded (ds) DNA as a function of length for lengths from 12 to 100,000 base pairs, where the force is applied to the 3'3' or 5'5' ends of the dsDNA. Molecules with 32 base pairs or fewer melt before overstretching. For these short molecules, the melting force is independent of the ends to which the force is applied and the shear force as a function of length is well described by de Gennes theory with a de Gennes length of less than 10 bp. Molecules with lengths of 500 base pairs or more overstretch before melting. For these long molecules, the melting force depends on the ends to which the force is applied. The melting force as a function of length increases even when the length exceeds 1000 bp, where the length dependence is inconsistent with de Gennes theory. Finally, we expand de Gennes melting theory to 3'5' pulling and compare the predictions with experimental results.
authors.affiliation: Department of Physics, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Claudia
authors.initials: C
authors.lastname: Danilowicz
authors.forename: Kristi
authors.initials: K
authors.lastname: Hatch
authors.forename: Alyson
authors.initials: A
authors.lastname: Conover
authors.forename: Theodore
authors.initials: T
authors.lastname: Ducas
authors.forename: Ruwan
authors.initials: R
authors.lastname: Gunaratne
authors.forename: Vincent
authors.initials: V
authors.lastname: Coljee
authors.forename: Mara
authors.initials: M
authors.lastname: Prentiss
mesh_terms: D020029:Base Pairing; D001696:Biomechanical Phenomena; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D055595:Mechanical Phenomena; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D013816:Thermodynamics; D044366:Transition Temperature
chemical_list: D004247:DNA